AAg 2M[VO 4] 2 (A=Ba,Sr; M=Co,Ni): A series of ferromagnetic insulators

Angela Möller, Ngozi E. Amuneke, Phillip Daniel, Bernd Lorenz, Clarina R. De La Cruz, Melissa Gooch, Paul C.W. Chu

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27 引文 斯高帕斯(Scopus)

摘要

AAg 2M[VO 4] 2 with A=Sr2 + or Ba2 + present a series of layered compounds featuring a triangular lattice of transition metal cations, M = Co2 + or Ni2 +, connected via nonmagnetic ortho-vanadates, which provide the magnetic superexchange within the layers. For this series of insulating compounds, ferromagnetic long-range order below 10 K is suggested by magnetization and specific heat measurements and confirmed by neutron diffraction experiments. We have investigated the impact of the spacer size of A2 + separating the layers leading to a tilting of the vanadates and consequently inducing a change in the effective magnetic correlations. Magnetization and specific heat measurements corroborate the important dependence of the magnetic superexchange on the orientation of the vanadates and the respective spin system. Furthermore, the ground state properties of the spin systems, S=1 (Ni2 +) and S=3/2 (Co2 +) in their respective octahedral coordination of oxygen, are evaluated. Calculated magnetic moments of the single ion complexes agree well with the magnetic structure. We, furthermore, report the dependence of T c on applied isotropic pressure suggestive of a pressure effect on the effective ferromagnetic exchange coupling constants. In addition spectroscopic investigations probing the electronic structure of the [MO 6] complexes and the vibrational structure of the [VO 4] units are given.

原文English
文章編號214422
期刊Physical Review B - Condensed Matter and Materials Physics
85
發行號21
DOIs
出版狀態Published - 2012 六月 20

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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